Xhaka, who joined Leverkusen from Arsenal last year, has reportedly agreed personal terms with the Championship club, according to Sky Sports News. His agent confirmed to Sky Germany on Tuesday that a deal with Sunderland is in place "in principle."
However, Ten Hag has moved quickly to dismiss the prospect of an exit, emphasizing the midfielder's importance to the team - particularly following the departures of Florian Wirtz and Jeremie Frimpong to Liverpool, and Jonathan Tah to Bayern Munich.
"The agent can say anything," Ten Hag told German media. "But this club has already lost three important players. We won't let any more go - that would undermine both the structure and the culture of the squad."
Xhaka has three years remaining on his current contract and is viewed as a key leader within the Leverkusen dressing room.
"It's clear - Granit is a leader. He signed here for five years, and we have no intention of letting him leave. He's too important to what we're building," Ten Hag added.
With Leverkusen undergoing significant changes, Ten Hag appears determined to hold onto the core of his squad - and for now, Xhaka remains central to those plans.